摘要: The Great Plains of North America once covered over a million square miles through the center of the continent. The eastern third of this prairie ecosystem, from Manitoba, to Illinois and south to Texas, is known as the tallgrass ... 展开 The Great Plains of North America once covered over a million square miles through the center of the continent. The eastern third of this prairie ecosystem, from Manitoba, to Illinois and south to Texas, is known as the tallgrass prairie region. The tallgrass prairie, like the Great Plains as a whole, was shaped under the disturbances such as regular fire, repeated grazing, and frequent droughts. Beneath these cycles of change and disturbance, decaying prairie plants assimilated nutrients and returned them to the ground, creating rich, dark soils considered some of the most fertile in the world. This tallgrass prairie region once stretched across almost 200 million acres, but today, less than 4 percent of the original tallgrass prairie remains. 收起